1. Field of the Invention
The present invention relates to a film forwarding means. More particularly, the invention relates to a means for use in association with a camera employing film in the form of individual film units and for forwarding successive film units from an exposure station in a camera and into engagement with processing rolls or similar means in the camera.
2. Description of the Prior Art
There is known a photographic process, frequently referred to as `auto-process`, according to which film is provided not in roll form but in the form of individual units each of which comprises at least a negative image layer and a transfer image layer and has associated therewith processing solution contained in breakable pods, which are usually embedded in an edge portion of the film unit. The negative image layer is exposable to form a negative or latent image of an object, and a corresponding, viewable image may be formed on the transfer image layer under the influence of the processing solution, which is extruded from the pods and spread through the film unit under the action of pressure means between which the film unit is passed subsequent to exposure, which are conveniently provided as processing rolls, for example, mounted inside the associated auto-process camera, and which also act to move the film unit to the exterior of the camera, whereby a finished photographic print may be made available to a photographer in a very short time after a film unit is exposed, without it being necessary for the photographer to proceed to a separate, specially equipped location for development and processing of film. An auto-process camera must therefore include means for positioning successive film units at an exposure station, processing rolls or other pressure means for processing exposed film units and moving the film units to the exterior of the camera, and means for forwarding successive film units from the exposure station to the processing rolls.
Conventionally, a film forwarding means is proposed by the Japanese Patent Application Ser. No. 49-30332 entitled `Film Forwarding Means` filed on Mar. 15, 1974 by the same assignee, in which application, there is disclosed means comprising a film engagement means which is reciprocally slidable between initial and terminal positions, carries a hook means to engage a film unit at an exposure station and draw the film unit from the exposure station and into engagement with processing rolls provided in a camera, and is caused to move by an actuation means which is itself actuated by a rotary drive element, which is rotatable about a fixed axis, and while moving over a certain portion of the rotary path travelled thereby causes the actuation means to move forwards, i.e., in a direction to cause forwarding of an exposed film unit. Each time the film engagement means reaches the terminal position it is retained thereat, together with the actuation means, be a retainer means until the camera shutter release means is actuated to effect exposure of the next film unit, whereupon the engagement means and actuation means are released and are returned to initial positions by the action of a spring means. During this return movement, it is necessary that the rotary drive be at a position, or be travelling over that portion of its rotative path wherein the same cannot contact the actuation means, since otherwise the film engagement means is liable to be moved into engagement with the retainer means before the former has moved to its initial position in order to engage the film unit which has just been exposed, and which would therefore fail to be forwarded. Accurate control of movement of the rotary drive means to cause stopping thereof in a required position is of course possible with conventionally known means, but such control means, being precision elements, are comparatively expensive and so increase camera cost accordingly, and also require extra space in a camera.
Accordingly, an essential object of the present invention is to provide a film forwarding means for use in a camera employing film in the form of individual film units which is simple in construction and can be manufactured at low cost with substantial elimination of the disadvantages inherent in the conventional film forwarding means.
Another important object of the present invention is to provide a film forwarding means of the above described type which is accurate in functioning, including a rotary drive means which is not required to be stopped in an exact position.
A further object of the present invention is to provide a film forwarding means of the above described type which is compact in size and readily incorporated in the camera with minimum space requirements.